In order to form fine patterns in manufacturing semiconductor devices or printed wiring boards, for example, a negative type photosensitive resin composition has been used. In the method, a photosensitive layer formed on a base material (a chip for semiconductor device, and a substrate for printed wiring board) by application of a photosensitive resin composition or the like is irradiated with active rays through a specified pattern so as to cure the exposed portion. Further, the unexposed portion is selectively removed by a developer so as to form a resist pattern as cured film of the photosensitive resin composition on the base material. The photosensitive resin composition is therefore required to have high sensitivity to active rays and to be excellent in formability of fine patterns (resolution) and the like. Accordingly, a photosensitive resin composition containing a novolac resin soluble in alkaline aqueous solution, an epoxy resin and a photo-acid generator, a photosensitive resin composition containing an alkali-soluble epoxy compound having a carboxyl group and a photo-cationic polymerization initiator, and the like have been proposed (for example, refer to Patent Literatures 1 and 2).
Further, a surface protective film and an interlayer insulating film for use in a semiconductor device are required to have insulation reliability such as heat resistance, electrical properties, mechanical properties and the like. Accordingly, a photosensitive resin composition which further contains a cross-linkable monomer has been proposed (for example, refer to Patent Literature 3).
Meanwhile, along with improvement in performance of electronic equipment in recent years, higher integration and higher reliability of semiconductor devices have been achieved year by year. Along with high integration of semiconductor devices, the formation of further finer patterns and entirely thin-filmed semiconductor devices are required. In thinning of the entire semiconductor device, however, a warp caused by the difference in thermal expansion coefficient between a chip and a surface protective film or an interlayer insulating film becomes a serious problem. Consequently a photosensitive resin composition is required to have a thermal expansion coefficient close to the thermal expansion coefficient of the chip (3×10−6/° C.). In other words, reduction in the thermal expansion coefficient is strongly required. Accordingly, in order to achieve the reduction in the thermal expansion of a photosensitive resin composition, for example, a photosensitive resin composition containing an inorganic filler has been proposed (for example, refer to Patent Literature 4).
Further, when the interlayer insulating film having an increased thickness is formed, the insulation between wirings in the thickness direction of the layer can be enhanced to prevent short circuiting of wiring, and therefore the reliability of the insulation between wirings is improved. Further, in a case of mounting a chip, when a semiconductor device has a thick interlayer insulating film, the stress applied to the pad from a solder bump can be relaxed, so that connection failures hardly occur in mounting. Accordingly, in terms of the insulation reliability and the productivity in mounting a chip, a thick film of photosensitive resin composition with a thickness more than 20 μm is also required to be formed.